headline today, the terror attack on an american embassy a suicide bomber targeting the embassy in turkey. Is this the future plan of attack for terrorists? Abc's chief global affairs correspondent martha raddatz with the latest tonight. Martha? Reporter: This embassy suicide bombing happened on hillary clinton's last day as secretary of state. She was informed immediately and made calls all morning before turning her duties over to her replacement, john kerry, who tracked this all day. The blast was destructive and deadly. 1:13 in the afternoon, a lone male wearing a suicide vest beneath his coat walked up to the u.S. Embassy. He approached a visitor's entrance -- the first point of access to the embassy nearly 500 feet from the critical main building. Several turkish guards were standing post, several more were behind bulletproof glass and steel gates. Turkish tv reported that a security camera shows the bomber panicked when a metal detector went off. The turkish guard then shouted to others, "run away, a bomb." And the camera went black as the vest exploded. We have very good security to ensure people are stopped before they canlly get inside the fence inside the compound. That is exactly what happened. Reporter: The turkish guard was killed outright, several others hit by flying debris received minor wounds, and a turkish television reporter who happened to be entering the compound, was seriously wounded. Abc's nick schifrin is on the scene tonight. It was an absolutely terri terrifying scene. There is debris still visible but the building is intact. They were thankful that security sprentd something even more harm. Reporter: This is on the heels of the deadly assault in benghazi. But ambassador jim jeffrey, who served not only in turkey, but in iraq, said today's bombing shows that security at this embassy and u.S. Embassies in the region works. Kroiticcal a time when the tear e threat from new a al qaeda-linked groups especially is on the rise. This is how security is going to work. We cannot keep people from attacking us. Reporter: The white house says it is too soon tell who was behind the bombing but can't el fa size enough how the threat in the region is increasing from benghazi to algeria, americans have been under attack and there are very legitimate fears that will continue. Martha, thank you.

This transcript has been automatically generated and may not be 100% accurate.

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